## Re: JSLint rejects (n % 1)

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• ... My guess would be that JSLint treats (n % 1) in the same way that it treats (n * 1) and (n / 1). Perhaps it should not, since (n % 1) can return a value
Message 1 of 9 , Apr 27, 2011
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--- In jslint_com@yahoogroups.com, "Martin" <mbrrtt@...> wrote:
>
> JSLint rejects (n % 1) or (n % 1.0), which obtains the fractional part of a nonnegative number n. ("Unexpected '1'") Anybody know why?
>

My guess would be that JSLint treats (n % 1) in the same way that it treats (n * 1) and (n / 1).

Perhaps it should not, since (n % 1) can return a value that is not the same as n for both positive and negative values of n.

(n % 1) can, of course, b written as n - Math.floor(n) for n >= 0, and as n + Math.floor(-n) for n <0.
• The same happens to infinity operations in the form of n / 0: 1 / 0 === Infinity // true JSLint does not tolerate this kind of operation even though ECMA-262
Message 2 of 9 , Apr 27, 2011
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The same happens to infinity operations in the form of n / 0:

1 / 0 === Infinity // true

JSLint does not tolerate this kind of operation even though ECMA-262 11.5.2
says:

"Division of a non-zero finite value by a zero results in a signed infinity.
..."

In this case I'm with JSLint: Infinity keyword is clearer than 1 / 0

Marcel

On Wed, Apr 27, 2011 at 1:05 PM, Merlin <g7awz@...> wrote:

>
>
> --- In jslint_com@yahoogroups.com, "Martin" <mbrrtt@...> wrote:
> >
> > JSLint rejects (n % 1) or (n % 1.0), which obtains the fractional part of
> a nonnegative number n. ("Unexpected '1'") Anybody know why?
> >
>
> My guess would be that JSLint treats (n % 1) in the same way that it treats
> (n * 1) and (n / 1).
>
> Perhaps it should not, since (n % 1) can return a value that is not the
> same as n for both positive and negative values of n.
>
> (n % 1) can, of course, b written as n - Math.floor(n) for n >= 0, and as n
> + Math.floor(-n) for n <0.
>
>
>

--
Marcel Duran

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• Classification: UNCLASSIFIED Would it be possible to get this following list of names added to the assume a browser option: * Storage * localStorage *
Message 3 of 9 , Apr 28, 2011
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Classification: UNCLASSIFIED
Would it be possible to get this following list of names added to the "assume a browser" option:

* Storage
* localStorage
* sessionStorage
* globalStorage

Thanks,

Austin Cheney, CISSP
http://prettydiff.com/
http://prettydiff.com/beta
Classification: UNCLASSIFIED
• ... Do you really think that n % 1 is clever code , while n - Math.floor(n) is not? Sure, the operator % doesn t wear its meaning on its face. It s not
Message 4 of 9 , Apr 28, 2011
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--- In jslint_com@yahoogroups.com, "Merlin" <g7awz@...> wrote:
>
> Perhaps it should not, since (n % 1) can return a value that is not the same as n for both positive and negative values of n.
>
> (n % 1) can, of course, b written as n - Math.floor(n) for n >= 0, and as n + Math.floor(-n) for n <0.
>

--- In jslint_com@yahoogroups.com, mathew <meta404@...> wrote:
>
> Hence r = n - Math.floor(n). Which is what I'd write, because I hate
> 'clever' code.
>
>

Do you really think that 'n % 1' is 'clever code', while 'n - Math.floor(n)' is not?

Sure, the operator '%' doesn't wear its meaning on its face. It's not standard mathematical notation; you have to look it up the first time you see it, in a book or in the spec. But did you know what 'x || y' or 'x ? y : z' meant the first time you saw them?

'%' is in the language and straightforwardly computes what it is supposed to compute. n % 1 returns the fractional part of a nonnegative number. Perhaps -n % 1 (when n > 0) is tricky, but I don't need it and wouldn't use it, anymore than I'd use Math.sqrt(-n) to get NaN.

> My guess would be that JSLint treats (n % 1) in the same way that it treats (n * 1) and (n / 1).
>

I think this is may be the real reason why JSLint complains. As such, it is just a mistake: a bug in JSLint, not a feature. I would hope that Douglas Crockford fixes it, or else comes up with a much better reason why not.
• ... Yes. The meaning of n - Math.floor(n) is obvious. The meaning of n % 1 is not obvious, so much so that at least one person on this mailing list
Message 5 of 9 , Apr 28, 2011
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On Thu, Apr 28, 2011 at 07:46, Martin <mbrrtt@...> wrote:

> Do you really think that 'n % 1' is 'clever code', while 'n -
> Math.floor(n)' is not?
>

Yes. The meaning of 'n - Math.floor(n)' is obvious. The meaning of 'n % 1'
is not obvious, so much so that at least one person on this mailing list
misunderstood it.

> Sure, the operator '%' doesn't wear its meaning on its face. It's not
> standard mathematical notation; you have to look it up the first time you
> see it, in a book or in the spec. But did you know what 'x || y' or 'x ? y :
> z' meant the first time you saw them?
>
The problem isn't the meaning of '%'; I knew that % was remainder/modulo.
The problem is that extending modulo to floating point gives you at least
three different possible behaviors, as
http://en.wikipedia.org/wiki/Modulo_operation points out, and people's
expectations aren't necessarily met by those extended definitions.

mathew
--
<URL:http://www.pobox.com/~meta/>

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